MATERIALS AND METHODSBrown algae were collected in the littoral of theCanary Islands (Spain).Phenolic substances were extracted with 70% aqueousmethanol. Total phenolic substances were determinedby the Folin-Dennis method by development ofblue color (absorption at 725 nm) [10]. Floroglucinewas used as the standard.Isolation of florotannin from Cystoseira sp. Samplesof the collected algae were placed into liquid nitrogen.The frozen material was flooded with methanol(1 : 5 by volume). Extraction was carried out with continuousstirring in the dark at 3~ Two days later, themixture was filtered, and the extract was evaporatedin vacuo to a small volume at a temperature no higherthan 40~ The residue was supplemented with anequal volume of water, and methanol was removedin vacuo. To extract florotannin, the aqueous residuewas treated three times with ethylacetate.The resulting extract was dried above meltedNa2SO4, filtered, and evaporated to a small volume.Florotannin was precipitated from this extract byaddition of five volumes of chloroform. The precipitatewas dried in vacuo, and a powder of light cream colorresulted.
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